This invention relates to surface controlled subsurface safety valves used in the oil and gas industry and particularly including mechanism for temporarily locking the valves open.
It is well known to complete oil and gas producing wells with systems including subsurface safety valves controlled from the surface to shut off the flow in the well tubing string. Generally such valves are controlled in response to a control fluid pressure conducted to the valve from a remote location at the surface end of the well permitting the wells to be selectively shut in as well conditions require. The surface controller may be equipped to respond to emergency conditions such as fire, broken lines, and the like. Frequently it is necessary to conduct well servicing operations through such a valve and when such a valve malfunctions it may be necessary to install a second safety valve. In any such events, it may be desirable to either permanently or temporarily lock the valve open. For example if the well servicing operation require extending a wireline or similar equipment through the subsurface safety valve it is preferable to use a lock open system which is not dependent upon a control fluid pressure from the surface. Where operations are being carried out through an open subsurface safety valve such as pressure and temperature testing it can be extremely expensive and time consuming for a valve to malfunction closing on the supporting wireline causing damage to the wireline and sensing apparatus supported from the wireline along with additional well servicing procedures required to retrieve the equipment. Subsurface safety valve including both permanent and a temporary lock open mechanism are shown in the following U.S. Pat. Nos. 3,786,865; 3,882,935; 4,344,602; 4,356,867; and 4,449,587. The present invention particularly relates to a subsurface safety valve of the type shown in U.S. Pat. Nos. 3,786,865 and 4,449,587 employing temporary lockout arrangements for the flapper type of valve included in the subsurface safety valves.